:root {
    --primary-color: #2c3e50;
    --secondary-color: #34495e;
    --accent-color: #e67e22;
    --background-color: #f8f9fa;
    --text-color: #333;
    --card-bg: #ffffff;
    --font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

body {
    font-family: var(--font-family);
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
    margin: 0;
    padding: 0;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
}

header.hero {
    background-color: var(--primary-color);
    color: #fff;
    padding: 20px 0;    
    text-align: center;
}

header.hero h1 {
    margin: 0;
    font-size: 3em;
    font-weight: 700;
}

header.hero .tagline {
    font-size: 1.2em;
    font-weight: 300;
    margin-top: 10px;
    color: #bdc3c7;
}

section {
    padding: 0;
}

section h2 {
    color: var(--primary-color);
    border-bottom: 2px solid var(--accent-color);
    display: inline-block;
    padding-bottom: 10px;
    margin-bottom: 30px;
}

.intro p {
    font-size: 1.1em;
    margin-bottom: 20px;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 30px;
}

@media (min-width: 1000px) {
    .grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

.card {
    background-color: var(--card-bg);
    border-radius: 8px;
    padding: 25px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
    transition: transform 0.2s;
}

.card:hover {
    transform: translateY(-5px);
}

.card h3 {
    color: var(--secondary-color);
    margin-top: 0;
    font-size: 1.3em;
    border-bottom: 1px solid #eee;
    padding-bottom: 10px;
}

.card ul {
    list-style-type: none;
    padding: 0;
}

.card ul li {
    position: relative;
    padding-left: 20px;
    margin-bottom: 10px;
    font-size: 0.95em;
}

.card ul li::before {
    content: "•";
    color: var(--accent-color);
    font-size: 1.5em;
    position: absolute;
    left: 0;
    top: -5px;
}

.github-sources .repo-links {
    display: flex;
    flex-wrap: wrap;
    gap: 15px;
    margin-top: 20px;
}

.btn {
    display: inline-block;
    background-color: var(--secondary-color);
    color: #fff;
    padding: 10px 20px;
    text-decoration: none;
    border-radius: 5px;
    font-size: 0.9em;
    transition: background-color 0.2s;
}

.btn:hover {
    background-color: var(--accent-color);
}

footer {
    text-align: center;
    padding: 20px 0;
    background-color: var(--primary-color);
    color: #fff;
    margin-top: 40px;
}

footer p {
    margin: 0;
    font-size: 0.9em;
}

@media (max-width: 768px) {
    header.hero h1 {
        font-size: 2.5em;
    }
}